In a semiconductor product manufacturing process or a flat panel display (FPD) manufacturing process, a process of performing a liquid processing by supplying a processing liquid to a semiconductor wafer or a glass substrate as a substrate to be processed is frequently used. For example, such a process involves a cleaning processing that removes, for example, particles or contaminants attached to the substrate.
As for a liquid processing apparatus that performs such a liquid processing, there is known a single-wafer type liquid processing unit in which, when a substrate such as a semiconductor wafer is held and rotated by a spin chuck, a processing liquid (for example, a chemical liquid or a rinse liquid) is supplied to the front surface or front and rear surfaces of the substrate so as to perform a processing.
The processing liquid supplied to the substrate is shaken off from the rotating substrate, and formed and scattered as mists in an area around a substrate holding unit. Thus, a conventional liquid processing unit is provided with a drain section configured to recover the processing liquid that has been supplied to a substrate. Also, an exhaust section configured to exhaust the atmosphere surrounding the substrate held by the substrate holding unit is provided in the vicinity of the drain section. A liquid processing unit provided with a drain section or an exhaust section is known in the related art. See, e.g., Japanese Patent Application Laid-Open No. 2011-254019.